Colored roofing granules



AprH 25, 1961 J. R. LODGE ErAL 2,981,636

cOLORED RooFNG GRANULES Fi1ed Feb. 18. 1957 3. ance vvith tho Inethodsof the aff. In addition ceftai11 high intenSity colofS and paSte1 colofSnot obtainable by conventional InethodS can be pfoduced by oIf pfocess.Fnfthefn1ofe,the colofed coatings afe ffnlly bonded to the baSe gfanuleand afe substantially vvatef inSoluble and non-alkaline. T he coatingadhefes we11 to aSphalt foofing.

we afe able fo I1Se as a base gfanule any of a fathef vvide clasS offelatively pofouS of non-pofouS and weath ef-feSistant fock ofn1fnefalS. ExaInples of felafively pofoUS olatefial afe tfap fockS andSlates. Exan1ples of felatively nonpofous focks of IninefalS afeafgiHite of gfeyStone (Such aS the lafge gfeystone depoSits locatedabout ve Iniles nofth of vfausau, vvisconsin), gfeen stone, ceftaingfaniteS, etc. NofInally it iS pfefeffed to eIIlploy the felativelynon-pofouS focks, although even theso focks have a SubStantial pofosifyaS coo1pafed With ouf finiShed coatings.

Aq11eous SodinfI1 silicate is the pfefeffed alkali fneta1 Silicate, d11eto ifs availability and econonly, although equivalent Iflatefials SuchaS potaSSiun1 Silicate Inay alSo be Used. TT1e )fefeffed gfade ofSodi11n1 silicate solution is the socaned I bfand, Which haS a fatio of1`Ia to si0 of l=Z.84, a gfavity of 47 BauIn6, and a solidS content of404Z%. `Zafiations in the alkalinity of the Silicate .afe pefn1iSSible,b11t incfeaSed alkalinity faises the fequifeInents of the insolubiHZefand may, in soIne caseS, pfovide a Sn1an pefcentage of undeSifableSoluble alkali n1atefial in the ffflal pfoduct, vvhile exceSSive Siocontent feduces the filIn-fofn1ing pfopefties, as vvell as theconcentfation of the silicate. bfandS of sodiUn1 silicate SOlution n1aybe uSed. vVhen USing the O bfand, S1ightly Smanef amonnts ofinSolubiliZef afe feq11ifed to neutfaliZe the gfanule coating, Whenusing the 1) bfand of aqueous SodiuIf1 Silicate, 1afgef afflo11nts ofinSo111bilizef afe feqnifed,

IfI pfepafing aftificially colofed foofing gfanules in accofdance With apfefeffed efnbodiInent of the invention, the natufal ninefal iS cfUShedand scfeened to the doSifed size, eg. So aS t() paSS a n1eSh Scfeen andbe Tetained on a 351n eSh Screen. The gfanUles afe then heated to aten1pefatufe of ap foXin1ately 1101S0 F. and afe then Inixed with thesodinIn silicate solution in a suitable nlixef, Such as an ofdnafyconcfete n1ixef of othef tun1bling-baffel type of Inixef, A poftion ofthe tofal pign1ent content of the Sufface coating of the aftificiallycolofed gfanules Iflay be applied vvith the So diun1 Silicate solutionin the fofIn of a Sluffy, of, in Soffe caSeS an of the pigInent is aplied latef vvith the inSolubiHZef.

T,he coated gfanules afe then dfied, fvith fniniIflum agitation aS, fofexanlple, in a fotafy kiIn, at a ten1 pefatUfe above ZSO F, but below600 F., pfefefably about 400 F., to dohydfate the sHicate coating, vVhHethe gfanuleS afe at an elevated ten1pefatnfe of appfoXin1ately 350 F.,the pigInent and insolubiHzing agent such as an aqueous solution ofa111IninUfn chlofide of a InixtUfe of aluminum chlofide and amn1oniumchlofide afe applied to the hot gfanules, as by Spfaying. The inSolublepign1ent lTlay be caffied as a suspenSion in the inso111bilizingSolution, of the chlofido solI1tion and an aqueoUS pignent Suspensionn1ay be pfepafed and ap plied sepafately. The gfanllleS afe then colofedand nay then be tfeated with a pafain oi1, linSeed oil of any othefgfanUle ffeatInent knovvn to the foofing aft.

In the high teITlpefatufe eInbodiInent, the gfanuleS afe firSt n1ixedvvith a sluffy of a sodiun1 Silicate soll1tion, a hydfous plaStio cayand a poftion of the total pigfnent content. kilf1 to a ten1pefatufe ofabout 9501000 F- to feact the silicate and clay. SubSequently the coafedgfanules insolubiliZing agent afe appHed. The pigment may be S Spendedfn the insolubilizing SoII1tio11 of a sepafate 4 aqneous SI1SpeI1sion ofthe pigInent n1ay be pfepafed and applied.

The fonong pfefeffed fofnI11ae have been satiSfac tofily omployed fofthe pfoduction of aftificiaHy colofed f()ofing gfanuleS and ill11StfateSevefa1 Suitable cofnPoSitionS fof the coating of foofing gfanUlesvvithi11 fhe Scope of ouf invention,

1 Solids.

In coating one ton of gfanuleS accofding to the above fofn1Ula, thefoHowing pfocedufe Inay be satiSfactofily employed. A sl1ffy of thepigmentS, a we...ng agent pfefefably cofnpfiSing an anionicsnfface-acfive agent such aS S11lfoxy defivatives of hydfocafbons, a1dSodiun1 Silicadte so111tion is fifst nlade and is coated on the`gTanuleS in a Sllitable n1iXef Such as a fufnb1ingbaITe1 type of Inixef. Thegfanules afe fed into the n1iXef at 1101S0 F. and the Iflixing iscontinued until the gfanuleS afe unifofInly coated with the Sluffy. AifiS cifcIllated thfough the nlixef to dfy the gfanules; the paftialdfying Inay fe quire five to fen TI1in11tes. The gfanules afe then fed,pfefefably in a fotafy kiln at a tefnpefatufe of 3S0400 1 vv11ichtenlpefatufe iS nofn1any fflaintained fof ffoIn about five to tVventyIflif11tes depending Upon the siZe of the kiln and othef factofS todehydfate the silicate coat ing.

The gfanuleS 'afe tflen fed into a coolef, fof eXaInple a fotafy tube tye of coolef. AS the hot gfanuls Staft thfough the coolef, the feInaindefof the pign1ent and an inSolubiliZef Solution, aS Set fofth in the abovof()fff11la,

The coated gfanUleS afe then fifed in a fotafy afe applied fo thegTanuleS, In the above exaInple,it vill be noted that half of theheatSenSitive pigInent con tont (in this exafnple phthalocyanine gfeen)is appHed to the gfanuleS vVith the silicate bindef solution and fheotllef half with the insolubilizing agent. This fotio nlay be vafiodconsidefably, and an of the heat-senSitive pigfnent Inay be appliedvvith the inSolubilizing agent, aS in FofInUla No. Z. Te feSidIlal heatin the gfanuleS is at thiS point fnofe than SI1fficient to evapofate thevatef thus added and also to fen1ove any afnInonia libefafed ffofn theaInn1oniufn chlofide in solI1tionS including an1T1oniufn chloffde. TheteInpefatufe of the gfanules at the diS chafge end of the coolef is inthe ofdef of 200 F. ZS pfeviously IT1ontioned, the inSoluble pigmentInay be caffied aS a suspenSion in the solution of auminUn1 chlo fideand amInonium chlofide, of the chlofide solution aIld an aqueo11spignlent SUSpensio1 fnay be pfepafed and applied Sepafately. ThegfanuleS afe fhen oiled fof fhe pnfpoSe of incfeasing theif adhefence toaSphalt in tho pfeSence of Watef,

It may be desifable to on1it the yenow ifon hydfate ffoIn the abovefofInula and add a sfnall anlount of feffic chlofide, e.g., abont 1.5poundS SolidS, to the afofenoted inSolubiliZing solutioI1 and pignlentsuSpenSion USed tO tfeat the gfanuleS aftef dehydfation of fheff sodinn1silicate coating. The addition of SIflall `afnoutS of feffc Chlofidevvith thiS inSolubiliZing tfeatInent has been noted to pfoduce gfeencolofs Sifnilaf to of bfightef than those pfoduced vVith ye11ovv ifonhydfate in the IniXef foffflula.

vve have found that feffic chlofide, added in aoIleoIls -duce 11 Sitl1 ayeHow iron hydrate on the gran111e s111- faces. ThuS, ferric Chlo1 ideInay be nsed as heTe de scTibed i11 coobination With color pigTnents topTovide gTanuleS of vaTioUS colofs iT1cluding the lighteT and paSte1shades.

Te follovviIlg foTn1nla n1ay be used fo1 the pTepaTation of greengranules in which an of the heat-SeI1sitive gTeen pign1ent is app1iedvith the inSolI1bilizing solotion= FoIInula No. 2GTeen: Lbs. GTanules2000 Chrome oxide 100 Yenow iron hydTate 1.0 I bfand Sodiun1 Silicatesolution, 47

Banmo 300 watef 30 Insolubilizing Solution and pigment= AluIT1inumchloTide sollltion 2.0

Ammonm chloTide Solntion 1 20 Phthalocyanine GTeen 1 0.2

1 Solids.

The coating conlpoSition and inSolllbilize1 Solution and pigInent Inaybe prepafed and coated on Toofing gTanuleS in accofdance vvith fheInethod descTibed in connection With FoTmUla No. 1.

T1e fonoWin formula is inustrative of a com osition that n1ay beeInployed to pToduce a green granule in which an of the pigment isapplied With the insolubilizing agent.

Te coating con1poSition and inSoIubiHzing solution and pigTnent may bepfepared and ap Hed to the Toofing gTanuleS i1 accordance vVith the2Step n1ethod described in connection With FoTInI1la No. 1.

The follovving forInula iS illllStrative of the coating conlpoSitionsthat Inay be enlployed in the high teTTlperature eInbodinlent previouslyn1e11tioned, in which tho heat-SenSitive pignlent (in thiS exaInpleyellow iTon hy drate) is appHed with the inSolubilizing solution=FoTmula No. 4Ceam bu: LbS. Granules 2000 TitaninIn dioXide 500 Kaolin200 K brand sodium Silicate solution, 47 Baun 60.0 vvafef 200Inso1Ubilizing solI1tion and pigInent= Alon1inum chloride solution .75

Ammonium chlofide Solution .7S YenoW i on hydrate 20 Red iron oxide 0.2

1 so1ids.

zS in the n1efhod previonsly described, a slurry of titanillm dioxide,kaolin and sodiun1 Silicate solution is fiTSt pTepared and appHed fo thegtanUles in a Inixer of the type described. The granules and sluTry aTen1iXed foT SeveTal IninllteS 11ntil the glanllles are evenly coated, andthen they are dTied With a vvaTIT1 aif blast 11ntil they aTo of affeeoWing consiStency. The coated gTan111eS 6 are then fired iI1 arotary kiln fo a tenlperatuTe of about 9501000 F. toTeact the silicateand day. The granules aTe then fed into a coolef where the inSolnbilizeT SolUtion of aluIT1innIn chloTide and ao1Inoniun1 chlofideand the pigTnentS are added. The inSoltlbiliZe1' SolutioI1 neUtraHZesthe poTtion of the Soda content of the silicate that haS not reacted iththe kaoli11. 'The feSidual heaf in the gTanuloS is at thiS point Inofethan Sucient to evapoTate the Water thus added and alSo to Temove anyaInmonia liberated fTom the annoniUn1 chIoride solotion, AS in thepIocess deSofibed in con nection th ForInula No. 1, the pigTnents Inaybe SuS pended in the chlofide Solution of a Separate aqueous suspensionof the pigTnentS IIlay be pTepared. The teTn peTatuTo of the granules atthe diSchaTge end of fhe coole1 is likevviSe abont 200 F.

A pastel pink granule nlay be obtained by onitting the yenoW ironhydrate ffoIn the coating conlpoSition of FofInllla II(). 4. ()theTpaStel coloTS Such as gree11, yellow, etc. can be pfoduced iI1 1ikeInanneT by adding sn1a11 aInoonts of the following pigInentS vvith thein solobiliZing agent to a gTannle pfevioUSly coated vvhite vvithtitaninIn dioxide. vve have tlSed anoUntS of pig nlent as loW as thefollowing and fonnd theII1 to be effoctive in obtaining paStel Shades=Phthalocyanine gfeen 0.04 lb. (SolidS) per ton of gTanules.

1ed iTon o(ide 0.1 lb. (Solids) pe1 ton of grannles.

YeHovv iron hydrate 0.1 lb (SolidS) pe1 ton of gtanules.

The quantity of pigolent TequiTed for pastel granUles dependS on theColo1 StTeogth deSiTed, and it iS posSible IlndeI' ceftainciTcon1StanceS that even fhe forogoing SInall aInounts Inay be Teduced.

It iS to be undefstood that pign1entS other than thoSe specificallyn1entioned io the foregoing fofnlulae n1ay be eInployed. 0theI bTandS ofSodillIn Silicate solLltion, of a potasSiUn1 Siicate solI1tion, Inay beemployed iI1 ploce of tho I bTand sodiun1 Silicate soIntion specified inthe exan1pleS, LikeWiSe, the an11TonillIn chloride con tent II1ay beoInitted froIn the inSoluf)ilizing SoIution, in vvhich caSe thealuIni11IIIn oh1oTide conten iS increaSed correSpondingly.

ASphalt shingles suffaced vith granules coafed in accoTdance vvith theforegoing coating coInpositions have been exposed to the vveathe1 at St.PauL Minnesota, and at IouSton, TeXaS, foT peIiodS of tvvo yeaTS oflonger and have been found to have a Strongly boIded, veather reSiStantcoating that iS eSSentiany neut1a1 and has a low soluble salt content.

ThuS vve aTe able to produce artifically colofed g1an Ules in which apoTtion o1 all of the pigTnent is appHed to the gran111e sI1Tfaces aftelthe sodiun1 silicate bond haS been applied thereto and dehydfated.contTaTy to expectation the pignlent is adequately-bonded to the gTan11le. ]quaHy S11TpriSing is the fact that the colo1 in tenSity of Suchgranules is subStantially greater than the color intensity of granuleSin Which all of the pigTnent iS appHed With the sodium siHcate bond.Thus We aTe able to obtain the san1e coIo1 bTightneSS aS iS obtained inthe priOT methodS in Which all of the pigTnent is applied vvith thebond, by applying a poftioI of all of a red11ced an1ount of pigInent.Such as 40-0 less pign1ent, vith the insolubiliZing agent. While it iSdiicU1t to theofize as to fhe TeasonS fof this highly desirable reSult,it may WeH be that the piglnent, appHed With the inSolubilizing agent,acts in the nature of a lake on the gTan111e SIlTface, nluch asi11Soluble lakeS are foTn1ed vvitf1 ceftain organic dyes'tl1ffS in WhichaluIninUIn hydToxido is used as a InoTdant. T'here iS alSo a posSibilitythat the pigTIlent iS held in place to sonle eXtent by the silicic acidfor1ed by neutfalization of the sodiun1 silicate. ThiS theory nlayeXplain the eliInination of obiectionable vVhi te of gfay haze ofaltlfflintln1 hydfoxide, and of zinc of fIlagnesiun1 oxide of hydfoxidowhich iS 11()t found in gfanuleS fepafed in accofdanCe vvith the nethodShefe in deScffbed. LikeWiSe We afe ble to bond heatSenSi tive pigfnentsto gfanules coated by high ton1pefatufe methodS.

It is appafent that the in1pfoved coating pfoceSSes n1ay be 11Sed fofthe snfface coating of Inany types of gfan I1les of othef objectSlfanuleS, tiles of Slabs, Such as aSbeStosce1nent conlpositions of othefat pfefofffled caIcinable lit11ic Cen1ent slabS fnay silflilaffy begiven an inSol11bfe, vvelI bonded, neotfaL inofganic sI1ffacecoat ing byapplicatiof1 of all of a poftion of tlle igIflent With the inSolubiHZingtfeaffnent. In fhiS fflan11ef the effectiveneSS of the pigfnent iSincfeased, pfoducing a stfongef colof, of I)effnitting a feducfion infotal pigInent content to pfod11ce a Standafd colof.

That Which iS claifned is:

1. The method of colofing gfanoleS of the chafactef deScfibed whichcon1pfiSeS ap fying 'a coating of a hydfoUS plaSfic clay, a pigInent iI1an an1oUnt inSu0cient to pfovde the deSifed colof intenSity in thegfanule coating and Sodiofn Silioate, feacfing sai(i olay and silicateat teIn pefatufes of the oldof of 9501000 F., and applying difectlyIIpon the outef SI1fface of Said clay-silicate coat ing, a coInpoSitionconsisfing of additional pigInent and a soltltion of the coinpoUndadapted to co111plete the neutraIization of the soda content of saidcoating, to thefeby bond Said additional pfgInent on the outef SUffaceof said clay-Silicate coating by a nTafeffal consiSting of pfoductS ofthe chen1ical netfalization of safd undeflying coating.

2. Tfle method as defined in claifn 1 in which fhe Sec ond mentionedpigfnent is a pigment adapted to be daInaged at fenpefatufeS above 600F.

3. The nlethod of applying a co1ofed coating to the Sflfface offI1inefal gfanuleS co1T1pfiSing coating the gfanuleS vvith a iftlidfiIfnfofIning composition oonlpfiSing a pign1ent in af1 aInountiflStlfficient to pfovide the desifed colof st1-ength il1 the gfanUlecoating and an aqueouS solution of Sodium Silicate dehydfating theSilicate solI1- tion by heating the gfanuleS, then spfaying an aqueoUSn1ixtufe upon the gI'anuleS While they afe at a teInpefatufe of theofdef of at leaSt 200 F., the ingfedientS in said aqueoUS n1ixtufeconSisting eSSentially of a dfSSolved chen1ical inSolubiHzing agent fofSaid undeflying dehydfated sodiUn1 Silicate coating afld a SuSpendedpigInent, and thefI dfying the gfanules Said pign1ent applied with saidinsolubilizing agent being bonded on the outef Sufface of Saidundeflying siliCate coating by a n1atefial con- Sisting of pfoductS ofthe cheIT1ical insolflbilizatfon of said Undeflying coating,

4. The n1ethod of afticially colofing gfanuleS in the n1anufactufe offo00ng gfanules cofI1pfising coating the S11fface of the gfanuleS Vvithan aqUeoUS Solution of SodiuIT1 silicate, heating the coated gfanuleS totefnpefatufes of the ofdef of 400 F., and then applying a n1ixtufeconsiStif1g eSSentially of a pigInent and an inSolobiliZing so1LI tioncon1pfising one of Inofe IneInbefS of the gfoup con Sisting ofalunfinun1 chlofide, an1ffloniun1 chlofide, alufninufff SUlfate,Inagnesinn1 chlofide, Zinc chlofide and hydfochlofic acid whe thegfanuleS afe at a tempefatufe of the ofdef of 200 F,

5. Tho method of applying a cofofed coating to tho sul-face of Ininefalgfanules in the nanufactufe of foo011g gfantlles vvhich cofnpfisoScoating the Sufface of the gfanuleS vVith a nln1-fofIning cofnpositionoonsiSting eSSen tially of an aqueouS Solution of Sodiufn Silfcafe,Substan tiany dehydfating said Silicato solution by heaong the gfanules,and fhef1 applying a suS ension conSiSting eSSen tialy of a igInent anda neUtfaHzing SolI1fion to the SUf face of the coated gfanuleS vVhilothe gfanoles afe hot, Said Solotfon conSiSting of a lnixtofe ofalun1inun1 cho fide 'and aInInonium chlofide 6. Tfle fflethod ofaIfificaly colofing gfanUles in the maoufactufe of foofing gfanUlescofnpfiSing Coating the SI1fface of the gfanules With an aqueoUSsollltion of sodiun1 Silicate, dehydfating the silicate coating by heating the gfanuleS, and then ffeating the dehydfated silicate coating ofthe gfanuleS While Said gfanules afe at a ten1- pefatufe of tfIe ofdefof at leaSt 200 F. With an aqueouS solUtion of an insolubiling agent fofSaid sodiun1 silioato coating, Said insolubiHZing solution including apiglTlent in Suspension and a Sna1l afflount of fefl-ic chlofide atleast sucient to feact With the dehydfated sodinn1 silicatecoating ofSaid gfanuleS to fofn1 a yellow ifon hydfate.

ficia1ly colofed foong gTanUle coInpfising a ff1inefal baSe gfanIllehaving a )ign1ented insolubiliZed Silicate coating thefeon, and anofganic heat-SenSitive pign1ent bonded to the ontef SU1'face of SaidSilicate coating in an affloUnt pfoviding n111ch ITlofe intensepigfnentation on the Sufface than in the intefiof and Undeflyingpoftions of Said Silicate coating, Said heat-Sensitive pign1ent beingbonded on the sufface of said undeflying inSolubilized silicate coatingby an inSo111ble Inatefial conSisting of pfodncts of the cheInicalinS0ubifization of said tIndeflying silicate coating.

8. ZS a neW afticle of Inanufactufe: a non-hazy afti ficiaHy colofedfoofing gfanUle cofnpffSing a Ininefal baSe gfanUle having a chfoffleof(ide gfeen pigIflented in solUbilized silicate coating thefeon and aConcentfation of phthalocyanine gfeen pigInent on the sufface of Saidcoatfng in an afnount pfoviding fnuch Inofe intenSe pigfnentation on thesuffaco than in the intefiof and Undef lying poftions of said coating,Said phthalocyanine gfeen pigment being bonded on the sufface of saidundeflying insolubilized Sflicate coating by an insolUble fnatefialconsisting of pfoducfs of the cheIffical insolt1bilization of saidundeflying Silicate coating.

9. As a neW afticle of fnanL1factufe: a nonhaZy afti ficially gleencolofed fooflng gfanule cofnpfiSing a nioefal baSe gfanule having achfome oxide gfeen pigmented in S01I1bilized silfcate coating thefeonand a concentfation of a phthalocyanine gfeen pigfnont on fhe sufface ofsaid ooating in an afnount foviding the sufface of said coat ing wifhmnch mofe intenSe pign1entation than the intefiof and undeflyingpoftionS thefeof, Said coating coIf1 pfiSing a subStantially inSolublenonblooIning inofganic snicate feSUlting ffom the inSolubilizing ofsodium Silicate, and said phthalocyanine gfeen pigInent being bonded tosaid undeflying insoltlbilized silicate coating by an iI1- solIIbleInatofial conSisting of pfodncts of chenfical iI1 SolL1biIiZation ofsaid undeflying silicate coating.

10. NonhaZy afticiaHy gfeon colofed coated foofing gfanules havingintenSe gfeon SUfface colofatioo and fefa tively vveakef undeflyingcolofation in the coating thefe of, said foofing gfan fes coInpfising 3.IT1fnefal baSe gfan ule coated v/ith vvell-bonded, Substantiallynon-alkaline inSolubiliZed Silicate bindef n1atefiaL anda gfeen colofpigff1ent fiffnly bonded to the outef sI1fface of Said in SolubiHzedsilicate bindef fffatefial, Said colof pigInent being in subStantialfygfeatef concentfation of1the Suf face poffions of Said udef1yinginsolubilized silicate coat ing aS compafed to itS concontfation in theintefiof and undeflying poftionS of Said silicate coating, said colofpigfnent of1 SI1fface poftionS of said silicate coating being bonded toSaid undeflying inSolubiHZed silioafe coating by an inSoluble fflatefialconSisting of pfoductS of the chefni cal inSolubiliZation of saidundeflying sificate coatng.

ll, A nlethod of aftificiafly colofing gfanuleS in the fnanHfactufe offoofing gfanuleS coInpfising a1)Ilying U on the Sufface of nTinefaIgfanules a coating of a hy dfouS pfaStic clay and Sodioff1 Silicate,feacting said clay and Silicate at fempefatnfeS off the ofdef of 901000F., nd then ap lying a frli)(t[1fe ConsiSfing of a pigfnent and aninsolubifiZing SoIIltfon con1 fising one of Inofe fflefnbefs of thegfoup consiSting of a111fflin11ff ohlofide, affln1oniuIf1 chlofide,aI11n1inI1In sLllfate, InagneSiufn chlofide, zino chlofide andhydfoch1ofio acid vvliile the gfanules afe at a tempefatufe at 1oafo 1the o1-def of 200 F.,

fbefeby fo bond said pigoent app1fed With safd inSo1I1biHz ing so1ntiondifect1y upon the oute1 surface of said undef- 1yiog c1aysilicatecoating.

12. The Inethod of ap1ying a colored coating to the snfface of Ininefa1granuIes in the IT1anufacture of TooHng gfanU1eS Which coInpriSescoating the surface of the gTan l11es vvith a fi1In-foIn1ingcoInpositfon conSisting esSentially of an aqueouS Solution of sodiuInsilioate, SubstantiaHy de hydfating Said Silicate solotion by 11eatiT1gthe gTanu1eS, and then app1ying a SuspenSion conSisfing eSSentially of apignlent and a neutra1izing S()I1tion fo the sufface of the coatedgfanules While the gTanuleS are hot said S(1ution compfising one ofInore nleInbefS of the gronp consiSting of a1uIninun1 ch1ofide,an1nloniuxn chloride, a1Un1inIlm Sulfate, InagneSiun1 ch1ofide, zincchloride, and hydfo chlofic acid.

13. Non-hazy artificia11y co1ored foofing granules cofnpfising afflineTa1 base gfanule havin ga pignlented in so1ubiHzed silicatecoating theTeon and a co1or pignlent n11y bonded to the outef sufface ofSaid si1icate coating in an amount pfovided n1uch Inofe intenSepigInentation on the SUTface than in the fnterior and under1yingpoftions of said silioate coating, Said co1of pignlent on the sI1rfacepoftions of said siHcate coating being bonded to said undeTlyinginsolubilized silicate coating by an insoluble 10 mateTia1 conSisting ofproducts of tho chomica1 iosolobi1i' zatioI1 of Said undonying s11icatecoating.

14. Non-hazy afti1icia11y colofed foo1ing gfanu1eS oon1' I)Tising an1inefa1 base gfanu1e having a c1ay-silicate coat ing thereon and aheat-Sensitive coloI pign1ent 1irff11y bonded to the ontef sufface ofsaid clay-Silicate coating, Said 11eaf-Sensitive co1o1 pign1ent on thesufface of said clay-Si1icate coating being bonded to said undeHyingclaysi1icato coating by an insolub1e Iflatefia1 oonsisting of fe actionproductS of cheInical insolubilizat1oo of si1icate fn Said nndeflyingclay-Silicate coating.

Refeenoos c1fed in the file of this patent UNITED STATEs PATENTS Re.19,372 vvalton Nov. 13, 1934 1,898,34. Denning Fob. 21, 1933 1,939,930SmaH Dec. 19, 1933 Z,003,849 Alton Iuno 4, 1939 2,14Z,S veazey Jan. 3,1939 Z,163,678 Gundlach June 27, 1939 2,379,358 Iewett Iune 26, 1949Z,42Z,9Z7 1eyno1dS 1une 24, 1947 2,SS3,604 Pole May 22, 1951 2,S91,149(}Tove zpf. 1, 1952 Z,614,0S1 Buzzen of a1 ()ct. 14, 1992

1. THE METHOD OF COLORING GRANULES OF THE CHARACTER DESCRIBED WHICHCOMPRISES APPLYING A COATING OF A HYDROUS PLASTIC CLAY, A PIGMENT IN ANAMOUNT INSUFFICIENT TO PROVIDE THE DESIRED COLOR INTENSITY IN THEGRANULE COATING AND SODIUM SILICATE, RTEACTING SAID CLAY AND SILICATE ATTEMPERATURES OF THE ORDER OF 950*-1000*F., AND APPLYING DIRECTLY UPONTHE OUTER SURFACE OF SAID CLAY-SILICATE COAT-